1. Field of the Invention
The present invention relates to a sync code generation method, an information recording method, an information reproduction method, an information reproducing apparatus and an information storage medium. The present invention is effective as an information recording format and useful as a method of recording information into an information storage medium in an information recording/reproducing apparatus and as an method of reproducing information from the information storage medium. Further, the present invention is also usefully applied to a next generation DVD-ROM, a next generation DVD-R and a next generation DVD-RAM.
2. Description of the Related Art
The digital versatile disc (DVD) specifies the content of sync codes based on the current DVD format. This specification includes 32 kinds of the sync codes.
The information reproducing apparatus or information recording/reproducing apparatus employs the following method in order to detect a position of a sync code from reproduction data. That is, by matching reproduction data reproduced from an information storage medium with 32 kinds of patterns, it is determined whether or not a pattern match occurs.
This sync code position detection processing takes a great deal of time and labor. Consequently, the sync code detecting circuit becomes complicated thereby inducing an increase of price of the information reproducing apparatus or information recording/reproducing apparatus. As described above (because 32 kinds of sync codes exist), sync code detection algorithm is complicated. Thus, reliability of sync code detection is low. Further, a bit number of a code (bit number of an entire code) to be compared with a reproduction signal (32 bits of sync code) in terms of pattern is as long as 32 bits. For the reason, the error rate of a reproduction signal originated from a defect on an information storage medium is high and reliability of sync code position detection (timing detection) is low.
If considering the content of the sync code, three bit “0”s minimum may be continuous just before and just after a place where bit “0”s are continuous long (13 0s are continuous) in some case In such a case, deflection from synchronism in the phase lock loop (PLL) circuit is likely to occur, thereby reliability of sync code detection dropping.
Accordingly, an object of the present invention is to provide a sync code generation method capable of simplifying sync code position detecting processing and improving reliability of sync code detection. Another object of the present invention is to provide an information recording method, an information reproducing method, an information reproducing apparatus and an information storage medium, which employs the sync codes generated according to the same method.